Definition
A principle of fluid dynamics stating that as the velocity of a fluid (such as air) increases, the pressure within that fluid decreases, and as velocity decreases, pressure increases, provided the total energy of the fluid remains constant.
Plain English
When air speeds up, it pushes outward less; when it slows down, it pushes outward more. Fast air means lower pressure, slow air means higher pressure.
Context Anchor
Seen in aircraft systems and aerodynamics discussions, especially where airflow speeds up through a narrowed passage or around a curved surface.
Derivation
Named after Daniel Bernoulli, an 18th-century Swiss mathematician who first described the relationship between fluid speed and pressure in his 1738 work on hydrodynamics.
Why Pilots Care
It is the primary mechanism by which an airfoil converts airflow into lift, directly affecting climb performance, stall margins, and overall aircraft handling.
Analogy
Think of a garden hose. When you squeeze the nozzle, the water speeds up as it passes through the narrow opening. In the same way, air speeding up over a wing's curved surface drops in pressure compared to the slower air below.
Grounding Statement
Picture air speeding up as it passes through a narrower space; in that faster-moving area, the pressure drops.
Intuition Check
Do not think of Bernoulli’s principle as “faster air creates lift by itself.” It only describes the relationship between flow speed and pressure; the full explanation of aircraft lift includes other airflow effects too.
Example Sentence 1
Bernoulli's principle helps explain why faster airflow over the top of the wing produces lower pressure, contributing to lift.
Example Sentence 2
The maintenance manual referenced Bernoulli’s principle when explaining why a dent on the upper wing surface can reduce lift.